ИСТИНА

We constructed the Hilbert spaces of particle states in such a way that the fermions with the same electroweak quantum numbers (i.e. the neutrinos, the charged leptons, and the down- and up-type quarks) are placed in multiplets and are treated as different quantum states of a single particle. In a certain sense, in describing the electroweak interactions it is possible to use four fundamental fermions only in this model. In the theory based on the Lagrangian of the fermion sector of the Standard Model modified in accordance with this construction, the mixing and oscillations of the particles arise as a direct consequence of the general principles of quantum field theory. This approach enables one to calculate the probabilities of the processes taking place in detectors at long distances from the source. Calculations of higher order processes including the computation of the contributions due to radiative corrections can be performed in the framework of perturbation theory using the regular diagram technique. The developed approach is used to study neutrino oscillations. It is shown by the example of the pion decay that the states of the neutrino produced in the decay process can be described by a superposition of states with different masses and identical canonical momenta (the Pontecorvo states) with very high accuracy.